Analysis of CAG repeat of the Machado-Joseph gene in human, chimpanzee and monkey populations: a variant nucleotide is associated with the number of CAG repeats.

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder associated with an unstable and expanded CAG repeat. We analyzed this locus from various sources including MJD families, Acadian, African American, Caucasian, Greenland Inuit and Thai populations. The range of the CAG repeat size was 14-40 in the normal alleles while the MJD alleles contained 73-78 repeats in our studies.